The key proposition that is being contested in the test case is that the Wellington City Council did not apply the legal test for an earthquake=prone building. To be an earthquake-prone building, the building must exceed its ultimate capacity and be likely to collapse in a moderate earthquake. The Council switched the ultimate capacity test to ultimate limit state, and ignored the likely to collapse test altogether. The result is that the Council has been applying a much more demanding seismic capacity test than permitted by law.
All this is obvious and is obvious to MBIE. The issue was addressed in a paper presented to the 14th World Conference on Earthquake Engineering in 2008. The paper was written by Mike Stannard, MBIE’s Chief Engineer, and three others identified with the Department of Building and Housing. There is the following discussion.
“5.1 Definition of earthquake-prone building
The definition of earthquake-prone in the Building Act requires that the ultimate capacity of the building be exceeded and that it would be likely to collapse causing injury, death or damage to other property. Difficulties were expected in determining engineering criteria defining “ultimate capacity” and “collapse”. Even if it is accepted that “ultimate capacity” means attainment of the Ultimate Limit State (ULS) used in many design standards, the definition of “likely to collapse” poses difficulties. The difference between ULS and collapse states can be considerable depending on the configuration, integrity and ductility of the structure.(our emphasis) It is possible that engineers representing building owners will argue that collapse will occur at a much higher level than the ULS commonly used in assessment of structural performance.
There was pressure from design engineers to add regulations giving detailed definitions of how to assess the collapse level. The Department took the view that it would be easier to resolve such issues on a case-by-case basis. If a building owner does not agree with a TA’s view that a building is earthquake-prone, either party is able to refer the case to the Department of Building and Housing for a “determination”. This is a Building Act process whereby the Department examines the circumstances and “determines” if the Building Act and Code have been complied with. It was recognised that the lack of closer definition could give rise to requests for a “determination”, but the Department considered that these requests would be few in number on the basis that most owners of buildings with a ULS below or around the one-third threshold would not argue the finer points of ULS versus collapse. Rather, they would recognise the merit of strengthening work (our emphasis). If the Department receives many requests for determinations on this question, the need for regulations will be reviewed.”
We found this to be an extraordinary admission.
The Department knew that the ultimate limit state based assessment in the New Zealand Society of Earthquake Engineering guidance document, that most councils followed, was not consistent with the legal test. They said that “the difference between ULS and collapse states can be considerable”. But they activity promoted the use of the NZSEE’s ULS test in their own guidance material.
Engineers were asking for guidance on the application of the ultimate capacity and collapse tests, but the Department did nothing.
The Department knew that the use of the ULS test could be contested, but regarded the possibility as remote. Building owners would be too stupid to work out the difference between ultimate limit state and ultimate capacity, and could be duped into going along with the Department’s view of the world, which was to impose much higher seismic capacity standards than the law requires, and is economically rational.
We found the Department’s gloating over building owners’ gullibility, to a foreign audience, to be offensive.
The idea that the issue could be dealt with on a case-by-case basis strikes us bizarre. The law is the law and should apply equally to all building owners, not just to those who have worked out that the ULS test is unlawful.
What was not explained in the paper was that a Departmental Determination could not be an effective remedy. The Department would have to find that its own guidance was flawed. That was never going to happen, and did not happen in this case. Instead we were delivered a sham determination.
Many years have passed since the 2004 Building Act came into force and MBIE must have thought they had got away with it.
We will “argue the finer points of ULS versus collapse” before an independent New Zealand court.
We do not recognise that spending millions to strengthen a buildings with almost no perceptible impact on risk has “merit”.
 “Strengthening Buildings for Earthquake: Implementing New Zealand Legislation”
David C Hopkins, Mike Stannard, Graeme Lawrance, Ian Brewer Department of Building and Housing, Wellington, New Zealand